1. Field of the Invention
The described invention relates to testing of an integrated circuit. In particular, the invention relates to the testing of circuitry by providing an input via photosensors on the integrated circuit.
2. Description of Related Art
Integrated circuits are tested at the wafer level by supplying inputs via contacts. Input signals are provided to the integrated circuit by making physical contact with traces or bond pads on the integrated circuit: Testing is often done prior to the integrated circuit die being packaged to ensure that only functional die proceed to the packaging stage. As the need for testing increases, more bond pads are typically added so that more signals on the integrated circuit die may be probed. Often only one die can be tested at a time due to physical limitations of the machinery required to make physical contact with each integrated circuit die.
Contact testing of the integrated circuit can be costly in terms of the time required to connect to the contacts. Additionally, problems may arise with contact testing regarding the integrity of the connection to the bond pads as well as the integrity of the electrical characteristics of the integrated circuit itself, e.g., due to extra load on the circuit because of the contact connection.
An apparatus and method of testing an integrated circuit includes providing a first spectral input to the integrated circuit. A photosensor converts the first spectral input to a gating signal input that is used to gate a result output. The result output is checked to determine whether the integrated circuit is functioning properly. For one embodiment, the result output is used to provide a visual indication whether the integrated circuit is functioning properly.